1. Field of the Invention
The present invention relates to apparatus and method for determining the presence or absence of a disk and the size of a disk loaded onto a disk holder of a multi-disk changer including a plurality of disk holders, each holder being able to selectively accommodate a disk of different size.
2. Description of the Related Art
FIG. 1 is a simplified plan-view of a conventional multi-disk changer, and FIGS. 2A and 2B are drawings for the purpose of describing in detail the operation of determining the size of a disk inserted in the multi-disk changer of FIG. 1.
The multi-disk changer 1 of FIG. 1 includes a plurality of disk holders 11 to 14, each being able to accommodate disks of different sizes, for example, a 12-cm compact disk (CD) and a 12-cm digital versatile disk (DVD), or an 8-cm compact disk. Two through-holes 21 and 22 to be used for determining disk size are formed in each disk holder.
As shown in FIG. 1, one of the two through-holes 21 and 22 is located inside 8-cm diameter of a disk holder and the other is between 8-cm and 12-cm diameter. And, the two through-holes 21 and 22 are also aligned along a line A-Axe2x80x2 through the center of a disk turntable, as shown in FIG. 2A.
FIG. 2B is a cross-section taken along the line A-Axe2x80x2 in FIG. 2A. As shown in FIG. 2B, a pair of a light-emitting element 30a (or 31a) and a photo-detecting element 30b (or 31b) are placed above and below each through-hole 21 (or 22) such that a light-beam from the light-emitting element 30a (or 31a) is transmitted to the photo-detecting element 30b (or 31b) through the corresponding through-hole 21 (or 22).
Each detecting sensor composed of the pair of light-emitting element 30a (or 31a) and photo-detecting element 30b (or 31b), is used to detect the size of the disk placed on the disk holder 11. For example, if an 8-cm disk has been placed on a 8-cm holding space 112 formed in the disk holder 11, a light-beam from the inner light-emitting element 30a is blocked by the presence of the disk so that the corresponding inner photo-detecting element 30b can not detect any light-beam. However, the outer photo-detecting element 31b can still detect a light-beam from the outer light-emitting element 31a because the outer through-hole 22 is not blocked by the disk. In this case, it can be determined that the placed disk is 8-cm.
If a 12-cm disk is placed on a 12-cm holding space 111 formed in the disk holder 11, the two light-beams from both light-emitting elements 30a and 31a are blocked by the 12-cm disk so that the two photo-detecting elements 30b and 31b can not detect any light-beam. The detection of no light-beam means that a 12-cm disk has been inserted.
When two light-beams from both light-emitting elements 30a and 31a are detected at both photo-detecting elements 30b and 31b, no disk has been inserted in the disk holder 11, so that the light-beam detection by two photo-detecting elements 30b and 31b means that there is no disk in the disk holder 11.
According to the above-described operations of the detecting sensors 30 and 31, both the presence or absence of a disk and disk size can be determined at a time, and a servo control such as spindle motor control for rotating a loaded disk can be optimized for the determined disk size.
However, the above-described disk size determining apparatus in a multi-disk changer uses two detecting sensors to determine both the presence or absence of a disk and the disk size, so that the manufacturing costs of a multi-disk changer is increased.
It is an object of the present invention to provide a method and apparatus of determining the presence or absence of a disk as well as the disk size using only one detecting sensor in a multi-disk changer including a plurality of disk holders, each being able to selectively accommodate a disk of different size.
A disk size determining apparatus of a multi-disk changer according to the present invention, includes a turntable, a plurality of disk holders installed at the same distance from the center of the turntable, each disk holder being able to selectively accommodate a disk of different size, and a light-emitting element or a photo-detecting element above or below the turntable, wherein each of said disk holders has holes at the same distance from the center of the turntable, with a light beam passing through each hole from the light-emitting element in order that the disk size can be determined.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.